Q.An agent earns commission of 5% on the first ₹1,00,000 of sales and 8% on any sales above ₹1,00,000. If his total sales in a month are ₹1,80,000, find his total commission.

Split the sales at the ₹1,00,000 slab boundary and apply each rate separately.

First slab: $5\%$ of $100000=5000$; second slab: $8\%$ of $80000=6400$; total $=11400$.

This is a differential (slab) commission, so treat each slab of sales at its own rate.

First slab — the first $₹1{,}00{,}000$ at $5\%$:

Second slab — sales above $₹1{,}00{,}000$ are $180000-100000=₹80{,}000$, at $8\%$:

Total commission:

Check (independent verification): a flat $5\%$ on the whole $₹1{,}80{,}000$ would be $₹9{,}000$; the extra $3\%$ (from $5\%$ to $8\%$) on the top $₹80{,}000$ adds $\tfrac{3}{100}\times80000=₹2{,}400$, giving $9000+2400=₹11{,}400$ — matching.

Applying the higher $8\%$ to the entire $₹1{,}80{,}000$, or applying $8\%$ to the whole amount above nothing. Only the sales exceeding $₹1{,}00{,}000$ earn the higher rate.